Method and system for fractionation of lignocellulosic biomass

ABSTRACT

Methods and systems for fractionating lignocellulosic biomass including hemicellulose, cellulose and lignin, including exploding the biomass cells to devolatilize the biomass, hydrolyzing the hemicellulose to produce a liquid component including hemicellulosic sugars and a solid component including less than 10% hemicellulose, separating the liquid and solid components, vaporizing the cellulose in the solid component, and condensing the cellulosic sugar vapors. The methods and systems may vaporize the cellulose in a continuous steam reactor at a temperature of about 400-550° C. and a pressure of about 1-3 bara. Electromagnetic and/or electroaccoustic treatment such as ultrasound and/or microwave treatment may be applied to the biomass immediately before or during cellulose hydrolysis.

PRIORITY

This application claims priority to U.S. provisional patent applicationSer. No. 61/246,721, filed Sep. 29, 2009, the disclosure of which ishereby incorporated by reference in its entirety.

BACKGROUND

It is now generally accepted that fossil fuels are both limited as aresource and cause a net increase in global emissions of carbon dioxide,a “greenhouse gas” implicated in a potential global warming scenario.These fossil fuels, in particular petroleum, are essential for theproduction of liquid transportation fuels and the vast majority oforganic chemicals, in addition to providing a significant proportion ofstatic energy generation.

The only significant alternative source for liquid transportation fuelsand organic chemicals is biomass, such as lignocellulosic biomass, andconsiderable effort has been expended over many decades to produceefficient and economic processes for the conversion of biomass into suchfuels and chemicals.

Lignocellulosic or woody biomass is largely composed of hemicellulose,cellulose and lignin. Sources of lignocellulosic biomass include woodand wood residues, agricultural waste such as corn stover, woodygrasses, and residential and industrial waste. Each of the maincomponents of lignocellulosic biomass is a valuable material. Forexample, cellulose is principally comprised of C6 sugars (glucose) whichmay be further processed for the production of ethanol, a commercialfuel, or recovered as an anhydro-sugar, levoglucosan, or as levulinicacid and fine chemicals, mixed higher alcohols and more valuable fuels.Hemicellulose is comprised of C5 or C6 sugars such as xylose, arabinose,galactose, glucose and mannose. These sugars may be also fermented toethanol or recovered as furfural and other derivatives and furtherprocessed to fine chemicals, alcohols and other commercial fuels. Ligninis a complex polymer which may be further processed to fine chemicals(such as phenol and fuel additives) or may be used as a direct fuel forthe generation of heat and power for process and export.

The lignin component of lignocellulosic biomass materials gives physicalstrength to the biomass, and is tightly bound to the hemicellulose andcellulose components. Therefore, while it is desirable to fractionatethe biomass, the presence of the lignin makes fractionation difficult,and the harsh conditions required for fractionation can result inbreakdown of the carbohydrates into less desirable products.

Various methods have attempted to remove the carbohydrate sugars presentin hemicellulose and cellulose from the biomass. For example,biochemical and chemical processes using enzymes, solvents, acid,alkali, or hot water can be used to attempt to dissolve the carbohydrateor lignin components of the lignocellulosic biomass with or withoutconcomitant hydrolysis. In addition, various forms of pretreatment suchas steam explosion, hot water, and acid or alkali processes, attempt tomake the carbohydrates accessible for separation. However, separatingthe biomass into fractions and isolating each of these fractions, whileavoiding the production of byproducts and minimizing the consumption ofenergy (and therefore production cost) remains difficult.

The processes discovered to date for the conversion of biomass into fuelcan be generally considered to be included in one or other of thefollowing two categories. One category is a thermochemical treatment ofwhole biomass, without fractionation or separation of the componentparts of the biomass, by means of pyrolysis, gasification orliquefaction, generating primarily a crude bio-oil or synthesis gasmixture. The other category includes physical and chemicalpre-treatments of whole biomass, aimed at destruction or neutralization(rather than separation and collection) of the volatile or extractablecomponents and the hemicellulosic components of the biomass (which wouldotherwise inhibit the subsequent conversion step or steps), followed bya chemical or microbiological (enzymatic) hydrolysis of the cellulosiccomponents and a microbiological fermentation of the resultantcellulosic sugars. Other processes are also known which are generally ofa chemical nature and carried out in the liquid phase, such as solventdissolution and separation of one or more of the major components,including supercritical extraction processes. All such processes aregenerally directed at liquid transportation fuel production or atproduction of a specific chemical or limited range of chemicals or ofproducts such as fiberboard.

SUMMARY

Embodiments of the inventions described herein include systems, methodsand apparatuses for the fractionation of lignocellulosic biomass. Thisfractionation can be used for the recovery and isolation ofhemicellulosic and cellulosic sugars including C5 sugars and C6 sugars,lignin, and/or other biomass components. The fractionation can beperformed using continuous processes, such as one or more continuoussteam tubes, allowing for a rapid and efficient separation of thebiomass components.

Some embodiments of the present invention provide improvedthermo-chemical processing functionality. Some systems receive rawbiomass as input feedstock and produce relatively pure hemicellulosicsugars, cellulosic sugars and lignin as output. Some systems receiverelatively pure lignocellulosic solid as input and produce both isolatedsugars from the hemicellulose and a relatively pure lignin-cellulosesolid as outputs. Some systems receive relatively pure lignin-cellulosesolid as input and produce both isolated sugars from the cellulose and alignin char. In some systems, one, two, or all three of the systemsdiscussed in this paragraph can be included as sub-systems. Any of thesystems discussed in this paragraph can be implemented ascontinuous-flow processes.

In some embodiments, the invention includes a method of fractionatingand treating lignocellulosic biomass material including first, secondand third steam reactors. The method includes preparing the biomass byreducing its size, treating the biomass using superheated steam and/orEM/EA treatments, and feeding the treated biomass into a firstcontinuous superheated steam loop reactor to separate and hydrolyzehemicellulose and produce a solid and liquid component. The liquidcomponent includes hydrolyzed hemicellulose in water or an aqueoussolvent mixture and is separated from the solid component. The methodfurther includes optionally feeding the biomass into a second continuoussuperheated steam loop reactor to reduce the water content of thebiomass and/or to recover energy, feeding the solid component into athird continuous superheated steam reactor (e.g., a tube) to separateand hydrolyze the cellulose component and volatilize the products intothe vapor stream and to separate this from a lignin char, and condensingthe hydrolyzed cellulose and steam vapor.

In some embodiments, the invention includes a method for fractionatinglignocellulosic biomass material including feeding the biomass into adevolatilization reactor to separate and collect volatile components ofthe biomass, feeding the biomass into a hemicellulose hydrolysis reactorto separate and hydrolyze hemicellulose, separating the biomass into afirst solid component and a liquid component, wherein the liquidcomponent includes hydrolyzed hemicellulose in water or solvent andwherein the solid component includes cellulose and lignin and has lessthan about 10% hemicellulose, feeding the solid component into acellulose hydrolysis reactor comprising a continuous superheated steamreactor to hydrolyze and vaporize the cellulose component, andcondensing the vaporized cellulose. In some embodiments, the cellulosehydrolysis reactor applies steam to the biomass at a temperature of atleast 300° C. In some embodiments, the cellulose hydrolysis reactorapplies steam to the biomass at a temperature of between about 400 and550° C. The cellulose hydrolysis reactor may apply pressure to thebiomass at 1-3 bara. In some embodiments, the cellulose hydrolysisreactor applies steam to the biomass at a temperature of between about400 and 550° C. and at a pressure of 1-3 bara.

In some embodiments, the invention includes a method of isolatingcellulose from a biomass including feeding a biomass into a cellulosehydrolysis reactor, the biomass including lignin and cellulose and lessthan about 10% hemicellulose, hydrolyzing and vaporizing a portion ofthe cellulose in the cellulose hydrolysis reactor, separating thevaporized cellulose from a remaining biomass solid, and condensing thevaporized cellulose. In some embodiments, the method further includesfeeding the biomass into a hemicellulose hydrolysis reactor to separateand hydrolyze hemicellulose prior to feeding the biomass into thecellulose hydrolysis reactor. In some such embodiments, the methodfurther includes separating the biomass into a first solid component anda liquid component, wherein the liquid component includes hydrolyzedhemicellulose in water or solvent, wherein the solid component includescellulose and lignin and less than 10% hemicellulose, and wherein thestep of feeding a biomass into a cellulose hydrolysis reactor includesfeeding the solid component into the cellulose hydrolysis reactor.

The cellulose hydrolysis reactor may apply only steam to the biomasssolid, or it may apply a mixture of steam and another gas. For example,the reactor may apply a mixture of steam and nitrogen, hydrogen, carbondioxide, carbon monoxide, or combinations of more than one gas.

The cellulose hydrolysis reactor may also apply electromagnetic orelectroacoustic (EM/EA) treatment to the biomass. For example, thecellulose hydrolysis reactor may apply Pulsed Electric Field, ultrasonicenergy, microwave energy, or combinations thereof to the biomass in thereactor. In some embodiments, the cellulose hydrolysis reactor appliesultrasonic energy to the biomass, while in other embodiments it appliesmicrowave energy to the biomass, while in still other embodiments itapplies both ultrasonic and microwave energy to the biomass.

After hemicellulose hydrolysis and before feeding the biomass into thecellulose hydrolysis reactor, methods of the invention may feed thesolid component of the biomass into a dryer to reduce the water contentof the solid component. In some embodiments, the dryer is a continuoussuperheated steam reactor. In some embodiments, methods of the inventionmay include attriting the solid component after removing it from thehemicellulose hydrolysis reactor and before feeding the solid componentinto the cellulose hydrolysis reactor. For example, methods of theinvention may include first drying the biomass and then attriting thebiomass prior to cellulose hydrolysis.

The cellulose hydrolysis reactor may fully hydrolyze the cellulose toproduce a vapor of cellulosic sugars and a lignin char. The cellulosehydrolysis reactor may produce a vapor of cellulosic sugars and a secondsolid component. The second solid component may be fed into a secondreactor, which may be a superheated steam reactor. In some embodiments,the cellulose hydrolysis reactor partially hydrolyzes the cellulose, andthe second reactor is a second cellulose hydrolysis reactor thatcompletes cellulose hydrolysis and separates vaporized cellulosic sugarfrom the lignin. In other embodiments, the cellulose hydrolysis reactorcompletes hydrolysis of the cellulose and the second reactor reduces thelignin to a condensable gas that may be recovered.

Embodiments of the invention also include systems for fractionatinglignocellulosic biomass material including a means for releasingvolatile components from the biomass, a means for hydrolyzinghemicellulose in the biomass, a means for separating the biomass into asolid component and a liquid component wherein the liquid componentincludes hydrolyzed hemicellulosic sugars, and a means for hydrolyzingand vaporizing cellulose. The system may further include a means fordrying the solid component of the biomass after separation of the solidcomponent and the liquid component. In some such embodiments, the systemmay further include an attritor for attriting the solid component afterdrying. In some embodiments, the means for hydrolyzing and vaporizingcellulose includes an electromagnetic or electroacoustic generator toapply electromagnetic or electroacoustic treatment to the biomass.

In some embodiments, the method includes preparing a lignocellulosicbiomass material having intact cells for fractionation includingproviding the biomass, feeding the biomass into a superheated steamreactor at elevated pressure, heating the biomass with superheated steamwhile maintaining elevated pressure to explode the biomass cells withinthe steam reactor, and separating the exploded biomass from the steam.In some embodiments, heating includes heating the biomass to atemperature of between about 150° C. and about 190° C. within about 5 toabout 10 seconds. In some embodiments, the temperature of the biomass isincreased to between about 150° C. to about 190° C. and the pressure ismaintained at about 10 to about 15 bara. In some embodiments, thesuperheated steam reactor comprises a tubular structure wherein steamcontinuously circulates in a loop. In some such embodiments, the biomassflows through the reactor while entrained in the steam. In someembodiments, the method further includes applying EM/EA treatment to thebiomass within the reactor. The EM/EA treatment may include microwave,ultrasound, pulsed electric field, or a combination thereof.

In some embodiments, the method of preparing a lignocellulosic biomassmaterial having intact cells for fractionation further includesreleasing volatile components from the biomass into the steam. Themethod may also include separating the volatilized components from thesteam.

In some embodiments, the method of preparing a lignocellulosic biomassmaterial having intact cells for fractionation also includes feeding theexploded biomass into a hemicellulose hydrolysis reactor to hydrolyzehemicellulose, separating the biomass into a solid component and aliquid component wherein the liquid component includes hydrolyzedhemicellulose and wherein the solid component includes cellulose andlignin, and feeding the solid component into a cellulose hydrolysisreactor to hydrolyze the cellulose component and separate the cellulosicsugars from the lignin. The hemicellulose hydrolysis reactor and/or thecellulose hydrolysis reactor may be continuous superheated steamreactors.

Embodiments of the invention also include systems for preparing alignocellulosic biomass material having intact cells for fractionationincluding a tubular steam reactor, a steam inlet for entry ofsuperheated steam into the steam reactor, a blower to continuously movesteam through the reactor, a biomass inlet into the steam reactor forentry of the biomass material, and a biomass outlet within the steamreactor and downstream of the biomass inlet for removal of the biomass,wherein the reactor is designed to maintain the steam at a sufficienttemperature and pressure to rupture or explode the biomass cells as thebiomass passes between the biomass inlet and the biomass outlet. Forexample the temperature may be about 150° C. to about 190° C. and thepressure may be about 10 to about 15 bara. The blower may be designed tocirculate the steam at sufficient speed for the biomass to be entrainedwithin the steam and to pass from the inlet to the outlet in about 5 toabout 10 seconds. In some embodiments, the reactor comprises a steamloop wherein steam continuously circulates through the loop. The systemmay further include an outlet for separating and removing volatilecomponents of the biomass released by explosion of the biomass cells.

The system for preparing a lignocellulosic biomass material havingintact cells for fractionation may further include a source of EM/EAtreatment between the biomass inlet and outlet, such as a microwave,ultrasound, pulsed electric field generator, or a combination thereof.

Embodiments of the invention also include methods of fractionatinglignocellulosic biomass material including feeding the biomass into adevolatilization reactor, feeding the prepared biomass into ahemicellulose hydrolysis reactor to separate and hydrolyzehemicellulose, separating the biomass into a solid component and aliquid component wherein the liquid component includes hydrolyzedhemicellulose in water or solvent and wherein the solid componentincludes cellulose and lignin, feeding the solid component into acellulose hydrolysis reactor to hydrolyze the cellulose component, andseparating the hydrolyzed cellulose from the lignin, wherein EM/EAtreatment is applied to the biomass in the devolatilization reactor, thehemicellulose hydrolysis reactor, and/or in the cellulose hydrolysisreactor. The EM/EA treatment may include microwave, ultrasonic energy,pulsed electric field, or a combination thereof. The reactions in thereactors may be augmented, supplemented, or interspersed with the use ofEM/EA treatment.

In some embodiments, the EM/EA treatment is applied to the biomass inboth the hemicellulose hydrolysis reactor and the cellulose hydrolysisreactor. In some embodiments, the EM/EA treatment is applied at aparameter including frequency, pulse shape, power or duration, and oneor more of these parameters is adjustable. The EM/EA treatments can aidin cell rupture (lysis), especially at low temperatures, increase theheat transfer rate throughout aggregates of cells, increase cellmembrane permeability, degrade or reduce hemicellulose, cellulose andlignin polymeric structures, aid in hydrolytic and other reactions ofthe carbohydrate polymers, and aid the extraction of lipids, proteinsand non-carbohydrate components of cells.

In some embodiments, the hemicellulose hydrolysis reactor is arecirculating tube reactor. In some embodiments, the cellulosehydrolysis reactor is a tube reactor.

In some embodiments, the devolatilization reactor comprises asuperheated steam reactor at elevated pressure that rapidly heats thebiomass with superheated steam while maintaining elevated pressure toexplode the biomass within the steam reactor. In some such embodiments,the EM/EA treatment is applied to the biomass within thedevolatilization reactor. The method may further include releasing,separating, and removing volatile components of the biomass in thedevolatilization reactor.

In some embodiments, a system for fractionating biomass includes meansfor releasing volatile components from the biomass, means forhydrolyzing hemicellulose in the biomass, means for hydrolyzing andvaporizing cellulose, and a EM/EA generator for applying EM/EA treatmentto the biomass in one or more of the above means.

In some embodiments, the invention includes a system for fractionatinglignocellulosic biomass material comprising a first superheated steamloop reactor for exploding the biomass within the steam loop, a secondsuperheated steam loop reactor for hydrolyzing the hemicellulose, athird superheated steam loop reactor for reducing the moisture contentof the biomass, and a fourth superheated steam reactor for hydrolyzingcellulose into a vapor and forming a lignin char, wherein the biomass iscontinuously conveyed through the first, second, third and fourth steamreactors.

In some embodiments, the step of hemicellulose hydrolysis employs two ormore stages of continuous processing. In some embodiments, the step ofhemicellulose hydrolysis includes passing the biomass to a screw,extrusion or other conveyor system to continue hemicellulose hydrolysis.The hydrolyzed hemicellulose may be extracted using multi-stepsequential washing, with water or water/solvent mixtures, and dewateringat high pressures. Alternatively, the hydrolyzed hemicellulose may beextracted by passing the biomass to a pressure of about 1-2 bara andleaching with water or water/solvent mixtures. In some embodiments, thehydrolyzed hemicellulose is dewatered by applying a high pressure screwor extrusion presses to the biomass. In some embodiments, the residualbiomass solids include cellulose and lignin and less than 10%hemicellulose. The residual solids may then be attrited.

In some embodiments, energy is recovered in the form of high pressuresteam, part or all of which is superheated, such as the carrier steamfor the cellulose hydrolysis step.

BRIEF DESCRIPTION OF THE FIGURES

The following drawings are illustrative of particular embodiments of thepresent invention and therefore do not limit the scope of the invention.The drawings are not to scale (unless so stated) and are intended foruse in conjunction with the explanations in the following detaileddescription. Embodiments of the present invention will hereinafter bedescribed in conjunction with the appended drawings, wherein likenumerals denote like elements.

FIG. 1 is a schematic diagram of a system for the preparation oflignocellulosic material for fractionation;

FIG. 2 is a schematic diagram of an alternative system for thepreparation of lignocellulosic material for fractionation;

FIG. 3 is a schematic diagram of a devolatilization system;

FIG. 4 is a schematic diagram of a continuous flow steam loop reactorfor hemicellulose hydrolysis and fractionation;

FIG. 5 is a schematic diagram of another embodiment of a continuous flowsteam loop reactor for hemicellulose hydrolysis and fractionation;

FIG. 6 is a schematic diagram of an alternative embodiment of acontinuous flow steam loop reactor for hemicellulose hydrolysis andfractionation;

FIG. 7 is a schematic diagram of another alternative embodiment of acontinuous flow steam loop reactor for hemicellulose hydrolysis andfractionation;

FIG. 8 is a schematic diagram of a continuous flow flash thermolysissystem for the hydrolysis of cellulose and the fractionation ofcellulose and lignin;

FIG. 9 is a schematic diagram of an alternative continuous flowthermolysis system for the hydrolysis of cellulose and the fractionationof cellulose and lignin; and

FIG. 10 is a flow chart of a biomass fractionation process.

DESCRIPTION

The following detailed description is exemplary in nature and is notintended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the following description providespractical illustrations for implementing exemplary embodiments of thepresent invention. Examples of constructions, materials, dimensions, andmanufacturing processes are provided for selected elements, and allother elements employ that which is known to those of skill in the fieldof the invention. Those skilled in the art will recognize that many ofthe examples provided have suitable alternatives that can be utilized.

Embodiments of the invention may be used to provide a full fractionationof biomass into all of its constituent parts (such asvolatiles/extractables; hemicellulosic sugars; cellulosic sugars; ligninphenols; proteins; inorganic salts; etc.), while maintaining as much aspossible the structural complexity of the individual monomeric chemicalconstituents. It thereby permits a very wide range of chemical andliquid transportation fuel products to be produced in a flexible andeconomic manner. From these primary products, a number of which areplatform chemicals, the full complexity of the current organic chemicalsindustry can be recreated. The bio-oil produced is both less complex andless difficult, since it is primarily a product of cellulosic hydrolysisand depolymerization, with a much smaller contribution from othercomponents, as compared to other processes.

Furthermore, embodiments of the invention may be designed to provide alow residence time, continuous, vapor phase process which is thuscapable of extension to very large scales (such as 50,000 to 500,000barrels per day oil equivalent) at a single site. This ensures economiesof scale and matches the scale of petroleum refineries. The fuelproducts can thus be produced on scales commensurate with current globalpetroleum demand of 80 million barrels per day and secondary processing,on a bio-refinery complex, can be of equivalent current chemicalindustry scale.

Embodiments of the invention may also include the application oftechnologies not generally found in other such processes. Thesetechnologies may be employed to improve the heat and mass transfer toand from the biomass solids particles, which are generally limited inother processes and define the restrictions in their capabilities,thereby leading to increased yields and reduced reaction and residencetimes.

As such, embodiments of the invention may provide the primary componentof an integrated bio-refinery, generating platform chemicals and fuelbase stocks suitable for further chemical synthesis or refining, asappropriate.

Methods and systems of the invention include systems and processes forfractionating lignocellulosic biomass into monomeric and oligomericcomponents including C5 sugars and derivatives, C6 sugars andderivatives, lignin and other, minor, components. In some embodiments,some or all of the fractionation process uses a continuous flow process,making it possible to fractionate very large quantities of biomass withhigh efficiency and decreased cost.

The biomass is first prepared for fractionation. This preparationinvolves the standard operations normally involved for the specificbiomass used (cleaning, etc.) and may include reducing the size of thebiomass, deaerating the biomass, and/or pre-heating the biomass. It mayalso include the extraction of valuable components such as amino acidsor oils. The biomass is then opened up by some means of cell disruption,such as steam explosion. In some embodiments, the steam explosion uses aprocess of rapidly heating the biomass in a continuous steam loopreactor under increased pressure, exploding the biomass cells andremoving volatile components from the biomass. In other embodimentssteam explosion may be supplemented, augmented or replaced by EM/EAtreatments.

After preparation, extraction and devolatilization of the biomass, it isnext subjected to hemicellulose hydrolysis. In some embodiments, thehemicellulose hydrolysis includes a two stage process including a firststage high pressure steam loop to begin hydrolysis, followed by a secondstage holding system such as a conveyor system to complete thehemicellulose hydrolysis process. In other embodiments, the first stageof hemicellulose hydrolysis may include more than one high pressuresteam treatment, followed by a second stage holding system. Thehydrolyzed hemicellulose dissolves in aqueous solution and is separatedfrom the remaining biomass solid by a leaching system.

The biomass solid may then be dried to a desired moisture content andmay be comminuted to a fine particle size. However, in some embodiments,such as embodiments employing EM/EA treatments during cellulosehydrolysis, drying and comminution may not be included. The next step ishydrolysis of the cellulose. In some embodiments, the cellulosehydrolysis includes flash thermolysis. The flash thermolysis can beperformed in a continuous steam reactor under low pressure andtemperature, such as between about 350 and about 450 degrees Celsius.Under these conditions, the bond between the lignin and cellulose isbroken and the hydrolyzed cellulose may be removed in a vapor streamwith steam while the lignin forms a solid char. In some embodiments,cellulose hydrolysis is performed in two or more steps using two or moresuperheated steam reactors, with each subsequent reactor at a highertemperature than each previous reactor.

The methods and systems of the invention can be performed usingcontinuous systems such as continuous steam reactors (e.g., loops,tubes, etc.) and conveyor systems, for example, allowing for acontinuous processing system. As such, it avoids the time delaysinherent in systems which use batch processing. The continuousprocessing systems described herein are also more energy efficient thanbatch systems, because they do not require repeatedly increasingtemperature or pressure for each batch but rather the steam reactorsmust only maintain the desired temperature and pressure as the biomassmaterials enter and flow through the systems. Inherent accuracy ofcontrol permits a gradual increase of severity of treatment and resultsin a full and complex fractionation of the biomass.

Preparation of the Lignocellulosic Material

The biomass fractionation process begins with preparation of the biomassmaterial. Embodiments of the invention may use any lignocellulosicmaterial, such as hard or soft wood, grasses, agricultural waste, otherplant material, municipal waste, or a combination of one or more biomassmaterials. Examples of wood useful in embodiments of the inventioninclude pine, poplar, fir, spruce, larch, beech, oak, and palm trees andpalm waste, for example. The material may include wood from trunks,stems, branches, roots, heartwood, wood trimmings, wood bark, saw dust,wood pruning and forest residue, for example. Agricultural material orwaste which may be used in embodiments of the invention include, cornstover, corn cobs, corn kernels, corn fibers, straw, banana plantationwaste, rice straw, rice hull, oat straw, oat hull, corn fiber, cottonstalk, cotton gin, wheat straw, sugar cane bagasse, sugar cane trash,sorghum residues, sugar processing residues, barley straw, cereal straw,wheat straw, canola straw, and soybean stover, for example. Grasses mayinclude switchgrass, cordgrass, ryegrass, miscanthus, Bermuda grass,reed canary grass, and alfalfa. Other plant material may include woodand non-wooden plant material including stems, stalks, shrubs, foliage,bark, roots, pods, nuts, husks, fibers, vines, and algae. Municipalwaste may include residential waste such as waste paper and food andindustrial waste such as paper waste and board, papermill sludge andother cellulosic waste.

The biomass may be introduced into a preparation system from storage ordirect from transit. It may first be passed through bag slitting orother automated decontainerization process, if required, and then to ametal detection and removal process and/or a pressure or other washprocess, in which dirt and stones are removed from the biomass.

The biomass may then be conveyed and processed in a drying system, suchas an air blast or other drying system, to remove excess surface water.The clean biomass may then be passed on to one or more comminutionstages.

The lignocellulosic material undergoes comminution, such as by creatingchips or flakes, in order to attain a desired particle size. This may bedone by a flaking and sieving machine, a knife ring flaker withvibratory screen, for example. Particle size is chosen so as to keep thebiomass in suspension and to permit heat transfer through the biomasswithin the continuous reactor systems, which depends on steam velocity,biomass density, and biomass shape, among other similar factors. In someembodiments, the material is comminuted to about 0.5 to 5 mm thick andabout 12 to 80 mm in width and length. The preferred particle size maydepend on the diameter of the tubes employed in the subsequentprocessing steps. Some embodiments comminute material to about 0.5 to1.5 mm thick and about 12 to 15 mm in width and length. Some embodimentscomminute material to about 2 to 5 mm thick and about 60 to 80 mm inwidth and length. The preferred size of flakes measure about 1 to 3 mmthick, and about 25 to 40 mm in length and width in some embodiments.Preferred material sizes can also be expressed in terms of equivalentdiameters of spherical particles. Accordingly, preferred sizes may beabout 5 to 10 mm in equivalent diameter. In some embodiments havingcylindrical sections, such as grass type feedstocks, preferred sizes maybe about 2 to 5 mm in diameter and 25 to 50 mm in length. Particle sizeis a function of the system capacity and hence dimensions, as well asfeedstock characteristics, so that some embodiments may employ othersize ranges.

Some material may be determined by a sieve to be undersized. In someembodiments, a proportion of undersized material can be added to thematerial of the desired size for further processing, with the remainderbeing passed to different processing systems. In some instances, adifferent processing system can be a system for fractionating thebiomass, with the size of the system being configured to handle smallermaterial sizes (e.g., a smaller capacity, smaller diameter loop system).Oversized material can be recycled to the flaking or chipping machineand comminuted to the desired size. It is expected that a commercialsystem may have a number of reactor systems running in parallel, witheach system processing biomass material of a different size and/ordifferent feedstock.

In some embodiments, the biomass starting material may be comprised ofmany different materials, such as bark, twigs, and leaves. Processingsuch material to reduce its size also makes the material more homogenousand therefore better suited to processing. At the desired thickness,such as that described above, heat transfers to the center of thebiomass sufficiently quickly, making it a useful size for use in thesteam reactor processes described further below. In addition, the use oflong thin pieces such as flakes, for example, allows for pieces whichare thin enough for rapid heating but still have a sufficient size toallow for cyclonic separation of the solid biomass from steam, such asin a cyclonic separator, as may occur in various steps of thefractionation processes described herein. In some embodiments, theprocess of reducing the material size (e.g., by feeding, milling, andsieving) takes approximately one minute.

In some embodiments, the lignocellulosic material may be furtherprocessed to remove air from the biomass. This may be achieved byapplying a vacuum to the biomass and/or displacing air in the biomasswith an inert gas such as CO₂ or nitrogen. In some embodiments,subsequent steps of the fractionation process produce CO₂ which may becollected and used for deaeration of the biomass starting material. Insome embodiments, the biomass material is placed under a vacuum orpartial vacuum and an inert gas is drawn into the material, displacingthe air and removing oxygen from the material. The removal of oxygenfrom the material is desirable in order to reduce the level of oxidativedegradation of products and other undesirable reaction mechanisms, whichmay increasingly occur at elevated temperatures and pressures and in thepresence of acidic catalysts. The yield of sugars and other preferredproducts may be reduced by oxidative degradation, leading to reducedyields of fuel and other secondary products. Degradation can alsogenerate gaseous products, such as CO₂, which can result in waste of thefeedstock.

The preparation of the lignocellulosic material may optionally includethe removal and collection of volatile and other non-lignocellulosiccomponents such as essential oils, terpenes, amino acids, etc. wherethese components exist in significant proportions and have commercialvalue. For example, eucalyptus oil may be removed and isolated prior tofractionation of eucalyptus wood in order to extract the maximum valuefrom the feedstock. Proteins and amino acids may be removed from grassesand crop wastes, for use in animal feed or pharmaceuticals. Thesecomponents may be recovered for their commercial value and/or to preventinterference with the fractionation process or contamination of thefractionation products. They may be removed using a fully continuousprocess. In some embodiments, these components are removed through oneor more extraction steps. In some embodiments, the extraction stepscomprise a continuous countercurrent extraction process using one ormore solvents. The extraction step may utilize one or more EM/EAtreatments such as pulsed electric fields (PEF), ultrasonic energy (US)and/or microwave (MW) to lyse cells and to effect mass transfer of thecomponents of interest into the solvents. The EM/EA treatments may beapplied to the biomass either immediately prior to or during extraction.These extractions may be done at ambient temperature or at an elevatedtemperature, such as a temperature between ambient and approximately 150degrees Celsius, or between about 60 and about 120 degrees Celsius. Thesolvents may be chosen based upon the type of soluble component to beextracted. Examples of suitable solvents include hydrocarbons, such asmineral oil, ketones, alcohols and/or aromatics. In some embodiments, afirst solvent is applied to the biomass material and the solublecomponent or components are removed from the material by flowing thesolvent through the material, collecting the solvent, and isolating orseparating out the soluble component. A second solvent is then appliedto the material to allow the first solvent to be washed out using asubsequent water wash. The second solvent may also be collected and thesoluble component and/or first solvent may be separated out from thesecond solvent and isolated. For example, the second solvent may be bothhydrophilic and hydrophobic so that it is able to dissolve the firstsolvent and can then be washed out with the subsequent water wash. Oneor more water washes may then be flowed through the material. In someembodiments, such extraction steps can take approximately two-and-a-halfminutes, with each step taking approximately one minute plusapproximately 30 seconds for total feed and discharge.

The step of extraction of volatile and other non-lignocellulosiccomponents may be performed by counter-current or co-current continuousextraction equipment, such as a single or double screw conveyor orextrudor, a vertical plate extractor,a rotary extractor, or acentrifugal extractor, for example.

In some embodiments, the optional removal of volatile and othernon-lignocellulosic components may be provided as a side stream. In suchembodiments, the portion of a biomass for which extraction is desiredmay be diverted to the side stream, such as a series of countercurrentextractions as described above. The flow to the extraction side streammay then be stopped and biomass flow without extraction may proceeddirectly to the preheating step or to the hemicellulose hydrolysisreactor. In such embodiments, the flow of biomass from a preparationstage includes a branch for optional extraction or for bypassingextraction. Such systems allow flexibility in handling various biomassmaterials for which extraction may or may not be desired.

The lignocellulosic material may be further processed by preheating thematerial. For example, the material may be preheated using live steam(i.e., steam injected directly into the process), hot solvent orindirect heating. For example, in some embodiments, the material may bepreheated using low pressure steam. In some embodiments, the lowpressure steam may be applied to the material using a continuous processincluding a conveyor, such as a screw conveyor. The material may bepreheated to a temperature between approximately 100 and approximately200 degrees Celsius, such as a temperature between approximately 120 andapproximately 150 degrees Celsius. The material is preheated in order toreduce the thermal demand in the first steam reactor and to ensure thereactor operating temperature is rapidly attained. The temperature ispreferably kept below that at which significant hemicellulose hydrolysisoccurs, such as less than 180 degrees Celsius. In some embodiments, theprocess of deaerating and preheating the biomass can take approximatelytwo to three minutes.

In some embodiments, the process for removal of the non-lignocellulosiccomponents described previously is a hot solvent extraction process. Insuch a process, one or more of the solvents are at an increasedtemperature when applied resulting in heating of the biomass. The hotsolvents can therefore perform the function of pre-heating the biomassto a desired temperature as well as extraction.

In some embodiments, a water content adjustment step may be included tobring the water content of the biomass to the desired level. Forexample, it may be necessary to add water to dry biomass such as straw.Water may be added as steam or water during a preheating step asdescribed above. Alternatively, water may be added to thedevolatilization reactor to supplement the water released from thebiomass, to maintain the superheated steam mass flow rate required. Forexample, the water content may be increased to about 50%.

Embodiments of systems for preparing of a lignocellulosic biomassmaterial for fractionation are shown in FIGS. 1 and 2. A lignocellulosicbiomass material is fed from feedstock storage into a flaking andsieving machine 2 to reduce the feedstock to a desired size. Thefeedstock is then passed into a deaeration system inlet 4 and then intoa deaeration system 6 which removes the air from the biomass using avacuum 8. The vacuum is broken (or the air displaced) with an inert gas(N₂ or CO₂). The deaeration system 6 includes a conveyor, such as ascrew conveyor, which transports the biomass to the deaeration systemoutlet 10 through which the biomass exits the deaeration system 6.

In the system shown in FIG. 1, the biomass next passes to a first,second, and third solvent wash system 12, 14, 16, each of which includesan inlet 18, 20, 22 and an outlet 24, 26, 28, although alternativeembodiments could include more or less than three wash systems. In eachsolvent wash system 12, 14, 16, the biomass enters through the inlet 18,20, 22, is conveyed through the system 12, 14, 16 on or in a continuousprocessing unit such as a screw conveyer, and exits through the outlet24, 26, 28 to pass on to the next step of the process. The solvent washsystems 12, 14, 16 as shown are each countercurrent wash systems. Thefirst solvent wash system 12 uses a first solvent, and may also beequipped with one or more systems employing one or more of the EM/EAtreatment generators 29 (such as PEF, US, MW) which open up the cellsand enhance extraction of the components of interest into the solvent.The second solvent wash system 14 uses a second solvent. The solublecomponent dissolved in each solvent is recovered from each solvent washafter passing or flowing through the biomass. The solvents may then bereused for further solvent washes. Following the two solvent washes, thebiomass is washed in the third solvent wash system 16 with hot water,again using a countercurrent system. In some embodiments, the water isat a temperature of between about 90 and about 200 degrees Celsius. Inother embodiments, the water is at a temperature of between about 120and about 150 degrees Celsius. The solvent is removed from the biomassby the hot water, while at the same time the hot water preheats thebiomass to the desired temperature before the biomass passes to the nextstep of the fractionation process. In some embodiments, the next stageis devolatilization of the biomass.

An alternative biomass preparation system is shown in FIG. 2. In thissystem, there are no solvent washes and as such it may be used whenthere are no valuable extractives. However, the system may still employa hot water wash 16 as described with regard to FIG. 1. In suchembodiments, the hot water wash 16 functions to preheat the biomassprior to further processing.

It should be recognized that the systems shown in FIGS. 1 and 2 mayrepresent two distinct systems. Alternatively, one system may includeboth the process shown in FIG. 1 and the process in FIG. 2 asalternative pathways. In such an embodiment, the system may include adiverter valve or two separately controlled transfer feeders after thedeaeration stage allowing the biomass to optionally proceed throughsolvent extraction or to bypass solvent extraction and pass directly topreheating. Such a system may be used when a portion of the biomasswhich will be processed includes valuable extractives while anotherportion does not include such extractives.

One or more of the EM/EA treatments 29 (such as PEF, US, MW) can be usedin connection with one or more of the wash systems 12, 14, 16 to enhancethe performance of the wash systems 12, 14, 16. For example, one or moreof the solvent wash systems 12, 14 or the water wash system 16 mayinclude a pulsed electric field generator for applying PEF to thebiomass before it enters into, or as it passes along, the solvent washconveyor. The PEF may create holes in the cell walls which may allow formore rapid extraction of materials from the biomass. The PEF parametersvary with feedstock, but in some embodiments may include field intensity10 to 20 kv/cm, pulse duration 5 to 10 microseconds, pulse period 10 to20 milliseconds, and/or exposure time 0.1 to 0.2 seconds, for example.

Devolatilization

Embodiments of the invention include a process of devolatilization. Insome embodiments, volatile components (such as residual gases, lowmolecular weight organics and some oils and lipids) are removed from thebiomass by single or multi-stage steam distillation or flashvolatilization. In some embodiments, a unique form of steam explosionusing a continuous process of very rapid steam heating may be used tobreak apart the biomass cells. This process subjects the biomassmaterial to high temperature and moderate to high pressure, causingwater in the cells to expand and vaporize, leading to an increase ininternal pressure sufficient to rupture or explode the cells. In otherembodiments, the biomass is ruptured using a combination of steam andone or more of the EM/EA treatments in a similarly continuous process.

The continuous flow steam explosion (or enhanced steam rupture) processprovides several advantages, including continuously passing thebiomaterial through the system, fine control of processing conditions,improved energy conservation, and the ability to remove and collect thevolatile components contained within the biomass. The continuous flowsteam explosion (or enhanced rupture) process may be performed usingsuperheated steam, such as in a superheated steam tube such as a steamloop. The biomass is fed into the steam tube where it is exposed to thesuperheated steam, quickly raising the temperature of the biomass. Inaddition to cell rupture by simple steam heating, rupture may be causedby cavitation and cell wall permeabilization or poration. Because of thespeed of the heating, the steam is unable to diffuse out of the cellbefore it causes the cell to burst. Therefore, while the cells are stillunder elevated pressure and temperature within the steam tube, thebiomass cells burst or explode, opening up the cells. By rupturing thecell structure, the components become more accessible, allowing thesubsequent fractionation of hemicellulose, cellulose, and lignin.

In some embodiments, the superheated steam is at a temperature ofbetween about 120 and about 220 degrees Celsius and a pressure ofbetween approximately 6 and approximately 16 bara. In some embodimentsthe temperature is preferably between 150 and 190 degrees Celsius andthe pressure 10 to 15 bara. At this temperature and pressure, thebiomass can be heated up very quickly without forming a char orsuffering significant hydrolysis of the carbohydrate fractions.

The superheated steam may be flowing through a pipe, tube or similarstructure. For improved energy efficiency, the steam may flow in acontinuous loop under the force of a blower or fan. When the biomass isinjected into the pipe, it becomes entrained in the steam and isconveyed with the steam such that the particles of biomass are suspendedand moving through the pipe without settling to the bottom of the pipe.In addition, the steam and biomass may be conveyed through the system ata high velocity, generally at velocities of 10 to 25 m/s and preferablyat velocities of 15 to 20 m/s. By using this superheated steamentrainment process, the biomass heats up much more quickly than with astationary or batch process, allowing for the rapid heating required forthe steam explosion to occur. This can create a highly turbulent flow,which, together with the high temperature vapor and high surfacecondensation film coefficients, allows for faster transfer of heat fromthe steam to the biomass. It is believed that the steam condenses on theoutside of the biomass particle, causing heat transfer to the biomass byconduction, convection and radiation.

In addition, the use of EM/EA treatments, with the high velocity steam,can substantially increase the rate of energy transfer, from the periodsof hours or tens of minutes for batch processes to seconds, with PEF,for example, acting to open cell membranes in microseconds. The EM/EAtreatments may be applied to the biomass immediately before entering thedevolatilization tube or as it passes through the devolatilization steamtube. A portion of the tube may be a pulsed electric field generator,ultrasonic energy generator or microwave generator, directing the EM/EAtreatment into the tube. In some embodiments, PEF may be applied to thebiomass during devolatilization. Again, PEF parameters vary withfeedstock and may include field intensity 10 to 20 kv/cm, pulse duration5 to 10 microseconds, pulse period 10 to 20 milliseconds, and/orexposure time 0.1 to 0.2 seconds. In other embodiments, ultrasonicenergy may be applied to the biomass during devolatilization. USparameters may include frequency 20 to 40 kHz and/or exposure 30 to 90seconds. In still other embodiments, both PEF and ultrasonic energy maybe applied to the biomass during devolatilization. Either the PEF may beapplied first, followed by the US, or the US may be applied firstfollowed by the PEF. The US, for example, may heat the biomass cellsfrom the inside out, in a matter of seconds, while the steam transfersheat from the outside of the biomass inward. The US therefore allows fora faster and more efficient devolatilization process. In someembodiments, the entire process of devolatilizing the biomass can takeapproximately one-and-a-half to three minutes (including approximatelyfour to five seconds in a superheated steam loop).

The use of a superheated steam tube such as a steam loop for variousreaction processes including devolatilization and hemicellulosehydrolysis, for example, allows for precise control of temperature andpressure conditions as well as the entrainment time of the biomasswithin the system. In addition, the transit time of the biomass withinthe system can be controlled by controlling the speed of the blower toincrease or decrease the speed of the steam in which the biomass isentrained. Therefore the temperature, pressure and speed of the biomasscan all be carefully and independently controlled to optimize theprocess. A single loop residence time may be of the order of 5 to 10seconds.

The continuous flow steam explosion opens the structure of the biomasscells to allow for fractionation of the biomass and also releases thevolatile and non-carbohydrate components from the biomass, such asacids, oils, and terpenes (e.g., Turpentine and essential oils). Thevolatile components are vaporized by the elevated temperature and alsoundergo steam distillation due to the superheated steam. The steamdistillation process reduces the effective boiling point of certainvolatile components, such as organic components like oils, to atemperature which is lower than the pure component boiling point atatmospheric temperature, resulting in the volatilization of thecomponents at a lower temperature than would otherwise be required. Thismakes it possible to remove more volatile components than wouldotherwise be possible by heating to a specific temperature alone withoutthe presence of superheated steam.

The volatile components released by the steam explosion process can becollected, such as by allowing the vapors to pass to a gas collectiondevice such as a condenser, such as a direct contact condenser, scrubberor similar apparatus. The gas collection device may be provided in linewithin the steam tube or loop to allow for a continuous anduninterrupted flow of biomass material and steam and may operatecontinuously, allowing the steam and biomass to continuously flowthrough. In addition to removing volatile components, any remainingoxygen or any inert gases within the biomass may be removed by the steamexplosion process as well, thereby performing or completing thedeaeration process. The continuous flow superheated steam processtherefore results in devolatilization through flash steam distillation,steam explosion (with or without EM/EA treatment) of the biomass cells,and complete deaeration of the biomass.

Examples of continuous steam reactors which may be used for thedevolatilization process include, for example, conventional single ormulti-tube reactors with or without static or rotating internals, screwconveyors or extruders, fluidized bed reactors such as bubbling,spouted, or circulating bed reactors, ablative reactors, and, ingeneral, any single pass continuous system.

Prior to entering the steam reactor used for the continuous flow steamexplosion, the biomass is at atmospheric pressure, while within thesteam reactor it is at an elevated pressure. Therefore the biomass mustbe injected into the steam reactor using a solids feeding system whichcan operate against this pressure differential. In one embodiment, thesolids feeding system is a lock hopper/blow tank type system. Thissystem is a discontinuous system operated in a rapidly cycled manner,but may be made to operate in an essentially smoothly continuous mannerthrough the addition of a conveyor system such as screw or rotaryfeeder. In another embodiment, the solids feeding system is a solidspump, a centrifugal device in which friction is utilized to move solidsin a plug flow. Such solids feeding systems may be used at any of thevarious steps described herein where a solids feeding system is calledfor, or anywhere the biomass is transferred from one system or step toanother.

An embodiment of a system and process for continuous flow high pressuresteam explosion (and enhanced cell rupture) is shown in FIG. 3. Theprepared biomass, such as the biomass resulting from the process shownin FIG. 1 or FIG. 2, is fed into a solids feeding system 30. The biomassis then injected into the continuous steam loop 32 at a steam loop inlet34. A blower 36 in connection with the steam loop 32 pushes the steamand the entrained biomass through the steam loop 32. Within the steamloop 32, the biomass is rapidly heated using superheated steam at a hightemperature and pressure, optionally together with one or more of theEM/EA treatment generators 33, to disrupt or explode the cellularstructure of the biomass, release volatile components and prepare thebiomass for fractionation, while the biomass is conveyed within thesteam loop 32. The steam exploded, or disrupted, biomass travels throughthe steam loop 32 to a separator inlet 38, in line with the steam loop32 to enter the separator 40. The separator 40, such as a cyclonicseparator, separates the solid biomass from the steam and volatilizedcomponents. Steam exits the separator 40 along with the volatilizedcomponents and inert gases through a first separator outlet 42 tocontinue circulating through the steam loop 32. The steam andvolatilized components pass to a gas collection device 44, such as spraytower, which scrubs out the soluble volatilized components. Remaininginert and other gases and vapors pass on and a portion of these,together with a similar proportion of the steam, are removed from theloop under pressure control from pressure control device 46. Pressurecontrol device 46 can compensate for increased loop pressure caused byinert gases and low-boiling volatile vapors by venting some of thegases, vapors (and steam) to balance the pressure in the loop.Condensable components can then be condensed out by a condenser orremoved by a separate scrubber, for example, for recovery. The remainingsteam and gases recirculate back to the blower 36 and through the steamloop 32 for reuse. The exploded biomass exits the separator 40 through asecond separator outlet 48 to exit the steam loop 32 and pass to thenext stage of the fractionation process. In some embodiments, thebiomass passes onto the hemicellulose hydrolysis stage afterdevolatilization.

In some embodiments, the solids exiting the separator 40 are fed intoone or more additional steam explosion systems, such as one or moresteam loop 32 and separator 40 systems, to repeat the process of steamexplosion on any biomass that remains unexploded. In such embodiments,any additional volatile components may again be collected and the fullyexploded (or open) solid biomass may then be passed on to the next stepof the fractionation process.

Hemicellulose Hydrolysis

After the preparatory steps are completed, the biomass is now ready toundergo extraction of the hemicellulose. The hemicellulose may beremoved from the biomass by any method or combination of methods, suchas hot water, acid or alkali processes. In some embodiments, thehemicellulose is removed by hydrolysis using superheated steam. In someembodiments, the entirety of the preparatory steps can takeapproximately seven to nine-and-a-half minutes with oil extraction orfour-and-a-half to seven minutes without oil extraction.

In some embodiments, the hemicellulose is hydrolyzed using superheatedsteam, in a continuous process, such as by entraining the biomass in acontinuous steam reactor (e.g., a loop, a tube, etc.). Examples ofcontinuous steam reactors which may be used for hemicellulose hydrolysisinclude, for example, conventional single or multi-tube reactors with orwithout static or rotating internals, screw conveyors or extruders,fluidized bed reactors such as bubbling, spouted, or circulating bedreactors, ablative reactors, and, in general, any single pass continuoussystem.

In some embodiments, the steam is applied to the biomass at a pressureof about 10 to 35 bara and a temperature of about 170 to 250 degreesCelsius. In other embodiments, the pressure is 23 to 32 bara and thetemperature is 220 to 240 degrees Celsius. The temperature and pressureare sufficient to hydrolyze the hemicellulose while minimizing oravoiding degradation of the biomass material. While both the hydrolysisand degradation reaction kinetics are functions of time, temperature andconditions such as pH, they exhibit different optima, so that it ispossible to maximize recovery of product sugars by selection ofappropriate operating conditions. In some embodiments, a single steamreactor is used, while in other embodiments two or more steam reactorsare used in series with the conditions of each reactor selected toobtain different products.

In some embodiments, the hydrolysis step employs one or more of theEM/EA treatments, such as those discussed elsewhere herein, to improveheat transfer and aid in the hemicellulose breakdown. For example, oneor more of PEF, US or microwave may be applied to the biomass in, orprior to, the hemicellulose hydrolysis reactor. In some embodiments,ultrasonic energy is produced by an ultrasound generator within, orimmediately before, the reactor to direct ultrasonic energy to thebiomass as it enters into, or passes through, the reactor. Theultrasonic energy parameters vary with feedstock and desired reaction orproducts and may typically be: frequency 20 to 40 kHz or 200 kHz to 1MHz; duration 1 to 5 seconds or 30 to 90 seconds. The ultrasonic (ormicrowave) energy may provide a supplemental method of heating thebiomass in the hemicellulose reactor by heating the biomass internally,making the hemicellulose hydrolysis reaction quicker.

In some embodiments, the hemicellulose hydrolysis begins in a firstsuperheated steam stage or location, such as a continuous steam tube orloop, and then continues in a second superheated or saturated steamlocation or stage, such as outside of the steam tube or loop. In someembodiments, this second stage is at approximately the same temperatureand pressure as the first stage, with the second stage acting as aholding system, allowing the hemicellulose reaction which began in thereaction chamber or steam loop to reach completion. The biomass may bemaintained in this holding system for a sufficient time for thehemicellulose hydrolysis reaction to reach completion, such as about oneto two minutes, for example, at a desired temperature. Completion of thehydrolysis reactions could be carried out at a lower temperature, butlonger residence times would be required to complete hydrolysis. Theholding system may comprise a holding tank, for example, or may be aconveyor system, such as a slow moving conveyor. Alternatively, theentire process of hemicellulose hydrolysis may occur within a singlestage or location, such as by keeping the biomass in a reaction chamberor keeping it within the steam tube or loop for a longer time,sufficient for the hemicellulose hydrolysis reaction to reachcompletion. However, the length of the steam loop/tube is directlyproportional to the cost of the system, therefore it may be moreexpensive to lengthen the steam tube or loop than to include a separatesecond stage outside of the steam loop/tube.

The reaction process begins in the superheated steam environment.However, the two steps of the reaction do not necessarily correlate withthe two stages of the superheated steam process described above. Thesuperheated loop/tube section is employed to provide the heat transferto get the reaction started, aided, where desirable, by EM/EAtreatments. Thereafter the reaction parameters may be determined basedon economics and convenience. It should be noted that hemicelluloses andcelluloses are not single, pure molecules but mixtures of polymers,copolymers and cross-linked polymers, formed from a number of monomersugars. Each such polymer has its own hydrolysis kinetics.

In some embodiments, two or more hemicellulose continuous superheatedsteam reactors are provided in a series. The first reactor may be at alower temperature than the second reactor. If a third reactor is used,then the temperature of the second reactor may be lower than the thirdreactor. For example, the first hemicellulose reactor may partiallyhydrolyze the hemicellulose (using a lower temperature and/or shorterreaction time than the second reactor), producing oligomers, such asoligomers having 2-20 sugars. These oligomers and other products wouldthen be removed, such as by leaching or high pressure press, and theremaining solid component would then proceed for further processing. Inthe second hemicellulose reactor, hemicellulose hydrolysis could becompleted, producing hemicellulosic sugar monomers.

The hydrolyzed hemicellulose is next removed from the biomass. The C5and some C6 sugars produced by hemicellulose hydrolysis are generallysoluble in water and may be dissolved in the water surrounding andabsorbed into the biomass after exposure to the superheated steam. Thissolution can be a relatively complex sugar solution, comprising theparticular monomer sugars of the selected feedstock, plus some oligomersof the hemicelluloses and some sugars, oligomers, etc. of the cellulosesand sugar derivatives (anhydrosugars, etc.). Further contaminants caninclude residual volatiles, such as acetic acid, alcohols, etc. and anyother soluble components such as amino acids, mineral salts, etc.

In some embodiments, the sugars are removed from the biomass in a singleor in multiple stages, using additional water and sequences of washingand liquid/solid separation. For example, the C5 and C6 sugars may beremoved using a counter-current water flow to leach the C5 and C6hemicellulose sugars from the biomass solids. In some embodiments, theC5 and C6 sugars may be removed after first dropping the pressure, suchas to between about atmospheric and about 2 bara, and then venting thevapors to flash off some of the water containing the dissolved sugars.The flash steam, which will contain entrained sugar-laden liquor, may becondensed in a direct or indirect condenser and the recovered liquorsent for sugar recovery. The hydrolyzed hemicellulose sugars are thenleached from the biomass. In some embodiments, low pressure leachingemploys a counter-current water flow to remove dissolved hemicellulosicsugars. In other embodiments, the dissolved hemicellulosic sugars may beremoved using one or more high pressure wash and separation stages, suchas using extrusion or compression equipment such as high pressure screwpresses, and continuous wash equipment such as counterflow conveyors orscrews. In some embodiments, the dissolved hemicellulosic sugars may beremoved using both presses and low pressure leaching processes. In someembodiments, the entire hemicellulose hydrolysis and removal process cantake approximately one-and-a-half to three minutes.

The step of leaching or expressing the biomass for removal of thehemicellulosic sugars and separation of the biomass into a liquidcomponent and a solid component may be performed by counter-current orco-current continuous extraction equipment, such as a single or doublescrew conveyor or extruder, a vertical plate extractor,a rotaryextractor, or a centrifugal extractor, for example.

The isolated hemicellulose sugars including C5 and C6 sugar monomers andoligomers (and derivatives such as anhydrosugars, aldehydes, etc.) areuseful as individual products and have various commercial uses. In someembodiments, some C5 sugars and sugar derivatives may be used forfermentation, such as for the production of alcohols, including ethanoland higher alcohols, such as butanol. Such fermentation processes may beperformed in conjunction with the fractionation process or may beperformed separately. In some embodiments, the isolated C5 sugars may befurther processed, such as for conversion into other chemicals. Forexample, C5 sugars may be converted into furfural. Hemicellulosehydrolysis products may also be passed on for further processing inparallel with, or in conjunction with, cellulose hydrolysis products.Some of these processes are identified later, in the discussion ofcellulose processing.

An embodiment of a two stage system and process for continuous flowhemicellulose steam hydrolysis is shown in FIG. 4. Biomass, such as thedevolatilized biomass produced by the system of FIG. 2, passes to asolids feeder system 50, like the solid feeder systems previouslydescribed. The solids feeder system 50 injects the biomass into thecontinuous steam loop 52 at the steam loop inlet 54. The steam and theentrained biomass are moved through the steam loop 52 by the blower 56,which circulates the steam through the steam loop 52. The biomass flowsturbulently and heats up rapidly within the steam loop 52, beginning thehemicellulose hydrolysis. Again, an EM/EA treatment generator 58 mayalso be optionally employed in this loop. The biomass passes through thesteam loop 52 through the separator inlet 60 to the separator 62, suchas a cyclonic separator, which separates the steam from the biomass. Thesteam exits the separator 62 through a first separator outlet 64 tocontinue circulating through the steam loop 52. The heated biomass exitsthe separator 62 through a second separator outlet 66 and passes to theholding system 68, which in the embodiment shown is a slow moving screwconveyor at the same temperature and pressure as the steam loop 52. Thehemicellulose hydrolysis continues to completion within the holdingsystem 68. At the end of the holding system 68, the biomass is moved toa solids feeder system 70 and into the hemicellulose sugar leachingsystem 72. In the embodiment shown, water is flowed through the biomassto wash out the sugars in a countercurrent manner as the biomass movesalong the conveyor. The water exits the leaching system for recovery ofthe hemicellulose sugars. This low-pressure leaching can takeapproximately four-and-a-half to five-and-a-half minutes. Thehemicellulose sugars may then be separated from the water byconventional distillation or by techniques such as pervaporation andfiltration (using membranes), reactive distillation or extraction, forexample. The solid biomass from which the hemicellulose has been removedand which now includes cellulose and lignin passes out of the leachingsystem 72 and continues on for further processing. The solid biomass mayinclude very little hemicellulose, such as 5% to 10% by weighthemicellulose. In some embodiments, the solid biomass passes on forremoval of the cellulose sugars, such as by the system shown in FIG. 8.

An alternative embodiment is shown in FIG. 5. As in FIG. 4,hemicellulose hydrolysis is performed using a steam loop and a screwconveyor. In this alternative embodiment, the biomass containing thehemicellulose sugars passes from the holding system 68 to a first highpressure screw press 74 for dewatering the biomass, and then to mixingand washing screw 76. A second high pressure screw press 78 is shown inFIG. 8, where it also functions as a feed screw 81 for the drying stage.This high pressure expression can take approximately one-and-a-half tothree minutes.

An alternative system for hemicellulose hydrolysis is shown in FIG. 6having two hemicellulose reactors in series for stage one. The firsthemicellulose reactor and hemicellulosic sugar leaching system are asdescribed with regard to FIG. 4, although the reaction conditions (suchas temperature, pressure and reaction time) may be modified such thathemicellulose hydrolysis is incomplete. The hydrolyzed hemicelluloseproducts of the first hemicellulose reactor are leached out by theleaching system 72 and the residual solid including unhydrolyzedhemicellulose, cellulose and lignin are passed on to the secondhemicellulose hydrolysis reactor. The residual solid is repressurizedusing a solids feed system such as a lock hopper/blow tank system. Thesecond hemicellulose reactor includes the same components as the firsthemicellulose reactor but may apply different reaction conditions. Forexample, the time, temperature, or pressure may be such thathemicellulose hydrolysis is complete. The hemicellulosic sugar productmay be monomeric sugars, for example, and the residual solid may becellulose and lignin with only a small hemicellulose component, such asless than 10%. In the embodiment shown, the second hemicellulose reactorincludes a second solids feeder system 250, a second continuous steamloop 252 having an inlet 254 for entry of biomass and a blower 256 forcirculating steam. EM/EA treatments may be applied by an EM/EA treatmentgenerator 258. A second separator 262 includes an inlet 260, a firstseparator outlet 264 for steam to exit and a second separator outlet 266to pass the biomass to a second holding system 268 and then to a secondsolids feeder system 270 and into a second hemicellulose sugar leachingsystem 272.

A further alternative embodiment is shown in FIG. 7. In this embodiment,like in FIG. 6, there are two hemicellulose reactor loops in series. Inthis embodiment, however, after exiting the holding system 68, the waterincluding the hydrolyzed hemicellulose is removed using high pressurescrew presses as in FIG. 5. A first high pressure screw press 74dewaters the biomass, followed by a mixing and washing screw 76. Asecond high pressure screw press 78 is shown after the firsthemicellulose reactor, while the second high pressure screw press 78following the second hemicellulose reactor may be seen in FIG. 8, whereit also functions as a feed screw 81 for the drying stage. As in FIG. 6,the biomass is repressurized before entering the second hemicellulosehydrolysis reactor by the high pressure screw press 78.

In some embodiments, the solid component remaining after removal ofhemicellulosic sugars is further processed for removal of cellulosicsugars, such as by the processes described herein. In other embodiments,the solid component including cellulose and lignin and relatively freeof hemicellulose, such as having less than 10% hemicellulose, may beused for other processes such as for the production of fiberboard. Thecellulose and lignin solid may be combined with a traditional resin suchas urea or formaldehyde. Alternatively, the hemicellulose obtained asdescribed herein may be converted to a resin by separate chemicalprocessing and combined with the cellulose and lignin solid to makefiberboard.

Cellulose Hydrolysis

In embodiments in which biofractionation is continued, the cellulose andlignin in the remaining solid are separated from each other next. Thismay be done by solvent solubilization of lignin, by enzymatic or acidic(dilute or concentrated) hydrolytic processes or by high temperaturepyrolytic processes. In some embodiments, the cellulose biomass issubjected to flash thermolysis to break the cellulose lignin bonds,simultaneously hydrolyze the cellulose and vaporize the products of thehydrolysis.

After removal of the hemicellulose, such as by the process shown inFIGS. 3-7, the remaining solid biomass includes primarily cellulose andlignin. In many embodiments, on a dry basis, the remaining solid biomassis about 60-70% lignin and 30-40% cellulose, with small amounts ofinsolubles, such as inorganic salts. In some embodiments, the solidbiomass is dewatered to remove loose surface water, as may be requiredfor further processing. For example, the water may be removed by using ahigh pressure press. In some embodiments, the solid biomass has a watercontent of more than about 60%, such as about 60-75% before dewatering.After dewatering, the water content of the biomass may be reduced toless than about 60%, such as about 50 to 60%.

In some embodiments, the dewatered solid may then be dried using asuperheated steam reactor (e.g., a loop, a tube, etc.). The dewateringprocess produces high pressure steam. This additional steam may berecovered to be used as energy, and the pressure used in the dewateringprocess may be determined based on the energy recovery requirements.This energy recovery may occur through direct use of the steam inanother part of the fractionation process. In addition or alternatively,energy may be recovered after heat transfer to a clean fluid, such asthrough a pressure reducing turbo-generator to generate power. Systemswhich may be used for the step of drying the solid component of thebiomass include continuous steam reactors such as conventional single ormulti-tube reactors with or without static or rotating internals, screwconveyors or extruders, fluidized bed reactors such as bubbling,spouted, or circulating bed reactors, ablative reactors, and, ingeneral, any single pass continuous system.

The use of a steam tube or loop for drying also allows the dryingprocess to be continuous. Alternatively or additionally, in someembodiments, drying may be accomplished by direct contact with a hot,dry gas stream (such as combustion exhaust gases) or by a range ofindirect, continuous drying systems, including belt and rotary dryers.The biomass may be dried to a water content of about 1 to 10%, and suchas a water content of about 2 to 4%. In some embodiments, the dryingprocess can take one to two minutes (including four to five seconds inthe steam loop/tube).

In some embodiments, the remaining solid biomass is further processed toreduce its size. For example, the biomass may be chopped up into smallpieces using an attritor or grinder to reduce the solid to a finepowder. In some embodiments, a size range of about 0.5 to 5 mm diametermay be used while in other embodiments a size range of about 2 to 3 mmdiameter may be used. The size reduction is used in order to ensure thatthe particle rapidly attains the temperature at which thermolysisoccurs, such as within about 0.5 to 3 seconds. Attriting the biomass maybe used in embodiments in which the biomass will undergo flashthermolysis, for example. In embodiments in which cellulose thermolysisincludes EM/EA treatments, drying and/or attriting of the biomass may beoptional.

Flash thermolysis may then be performed by subjecting the biomass to avery highly superheated steam or inert gas, or a combination of steamand inert gas, optionally together with one or more of the EM/EAtreatments. The EM/EA treatments may be employed to increase the heattransfer rate and to assist in breaking microcrystalline structures ofthe larger, more complex polymer molecules. In some embodiments, one ormore of PEF, ultrasonic energy or microwave energy may be applied to thebiomass immediately before it enters or as it passes through thecellulose reactor or any subsequent reactors. As such a portion of thereactor may include an EM/EA treatment generator to direct EM/EAtreatment to the biomass prior to or as it passes through the reactortube, for example. In some embodiments, microwave energy is applied,while in other embodiments ultrasonic energy is applied, within stillother embodiments both microwave and ultrasonic energy are applied tothe biomass in, or before, the same reactor. The microwave andultrasound energy may be applied in either order, separately, in closeproximity, consecutively or simultaneously. This combination oftreatments may be particularly useful, as ultrasound energy may break upthe cellulose crystals, while microwave energy may provide rapidheating. In some embodiments, the ultrasound energy may be applied at afrequency of 20 to 40 kHz or 200 kHz to 1 MHz and a duration 1 to 5seconds or 30 to 90 seconds. The microwave energy may be applied at afrequency of 0.8 to 3 GHz and a duration of 1 to 10 seconds. In someembodiments, when EM/EA treatments are used in the cellulose hydrolysisstep, the steps of drying and/or attriting the biomass prior to feedingit into the cellulose reactor may be omitted.

Flash thermolysis may be performed using a continuous process, such asby feeding the biomass into a continuous steam reactor. In someembodiments, the reactor includes only steam as the carrier gas. Inother embodiments, steam is used in combination with an inert gas tohydrolyze and carry the biomass. Examples of inert gases which may beused include CO₂, CO, nitrogen, hydrogen, or combinations thereof.Certain carrier gases may result in reactions which favor the productionof certain cellulose products. As such, the carrier gas or gases may beselected and used according to the desired products. For example, theuse of hydrogen as a carrier gas can result in the production of lessoxygenated bio oils.

In some embodiments, the superheated steam and/or gas may be applied tothe biomass at a temperature of between about 350 and about 550 degreesCelsius. In some embodiments, the superheated steam and/or gas may beapplied to the biomass at a temperature between about 400 and about 450degrees Celsius. Actual temperatures are dependent on the feedstock andthe desired products. In some embodiments, the superheated steam and/orgas may be applied to the biomass at a pressure of between about 0 baraand about 4 bara, such as a pressure of between about 1 bara and about 2bara, depending on pressure losses in the system. By using theappropriate temperature and residence time, the bond between lignin andcellulose is broken and the cellulose is hydrolyzed by the steam into C6sugars and other volatile compounds which are vaporized. The solid whichremains after vaporization of the cellulose consists of a lignin char.In some embodiments, the presence of steam and the use of a temperaturethat is sufficiently low may be selected to substantially avoidpyrolysis of the biomass, which would cause the cellulose to form a muchlarger proportion of various hydrocarbons such as tars, oils and gases.Therefore, in such embodiments, the temperature of the thermolysisreaction must be high enough for hydrolysis but not too high or else thecellulose will pyrolyze and the chemical composition of the productswill be greatly altered. In some embodiments, thermolysis can takeapproximately 30 seconds to one minute (including one-half to fiveseconds in the reactor).

In other embodiments, cellulose thermolysis may be performed using twoor more continuous superheated steam and/or gas reactors. The reactionconditions of the first cellulose reactor, including temperature,pressure, reaction time, and carrier gas, may be selected such that thecellulose hydrolysis reaction favors production of one or more firstcellulosic products. For example, the first cellulose reactor mayproduce cellulose oligomers or an higher proportion of a specific C-6sugar. The second cellulose reactor and any subsequent cellulosereactors may have different reaction conditions, such as to completecellulose hydrolysis. In such embodiments, the second reactor may beconsidered a second cellulose hydrolysis reactor. For example, the firstcellulose reactor may be at a temperature of 350-500° C. while thesecond cellulose reactor may be at a temperature of 450-550° C., withthe temperature in the first reactor being less than in the secondreactor. In other embodiments, the second reactor may provide conditionsto pyrolyze lignin, in which case the second reactor may comprise alignin pyrolysis reactor. This may follow complete hydrolysis of thecellulose. For example, the first reactor may hydrolyze cellulose at atemperature of about 350-550° C. and the second reactor may pyrolyzelignin at a temperature of 450-650° C., with the temperature of thefirst reactor less than the second reactor. In still other embodiments,the cellulose hydrolysis may be performed partially by a first cellulosehydrolysis reactor to produce a first cellulosic sugar product and thencellulose hydrolysis may be completed by a second cellulose hydrolysisreactor. A third reactor (a lignin pyrolysis reactor) may then pyrolyzethe lignin. In such embodiments, the first reactor may be at atemperature of 350-500° C., the second reactor may be at a temperatureof 400-550° C., and the third reactor may be at a temperature of about450-650° C., with the temperature in the first reactor being less thanthe second reactor and the temperature in the second reactor being lessthan the third reactor.

In some embodiments, the final reactor may treat the remaining ligninfraction after removal of cellulose by one or more cellulose reactors togasify the lignin. Such a reactor may be a continuous steam reactor likethose used for cellulose thermolysis, but may apply a higher temperaturesuch as about 900-1200° C. to produce hydrogen and carbon monoxide whichmay be used for chemical conversion processes.

The vaporized C6 sugars and volatiles may next be separated from theremaining biomass and collected. In some embodiments, the remainingbiomass (such as lignin char) and vapors are passed into a separator forseparating vapors from solids, such as a cyclonic separator, which maybe in line within the steam loop/tube. The separated vapor includes thehydrolyzed cellulosic vapors, which can then be condensed, such as by adirect contact condenser, scrubber, or similar apparatus. These vaporsalso contain significant heat energy, which may be recovered. Thecellulosic sugars may then be extracted from the condensed liquid, suchas by any of the technologies listed earlier for hemicellulose products.The separated cellulosic sugars may include glucose, levoglucosan, andlevulinic acid, for example. The cellulosic sugars and the otherproducts collected may then be used for various commercial purposes orfor further processing, such as fermentation to produce alcohols, eitherin conjunction with the fractionation process or separately. Otherdownstream technologies which can utilize the primary products of thisfractionation process include Virent's Aqueous Phase Reforming process(for synthetic gasoline, jetfuel and diesel); Segetis Binary Monomertechnologies; and other catalytic conversion processes and chemical orbiochemical reaction processes.

The solid that remains after hydrolysis of the cellulose is a ligninchar. The lignin char may be further processed. For example, the ligninmay be chemically converted into other products, such as phenols,soluble lignosulphonates and, more generally, into a range of aromatic,cyclic and aliphatic feedstocks. Alternatively, some types of lignin maybe pyrolyzed to produce phenols for synthetic resins. In someembodiments, the lignin may be fed into a reactor like the cellulosereactor, as a final reactor. This lignin reactor may be used to pyrolyzethe lignin to produce phenolic products, for example. In otherembodiments, the lignin may be burned to produce energy, such as for theoperation of the fractionation system. In still other embodiments, thelignin may be gasified to produce hydrogen and syngas, with the hydrogenfinding use in reduction reactions of some of the other primaryproducts.

Thermolysis and pyrolysis may be carried out in simple, entrained flowtube reactors or fluidized bed reactors. Examples of fluidized bedreactor which may be used include bubbling fluidized bed or acirculating fluidized bed, or in special reactors, such as a rotatingcone reactor or other ablative type reactor. In embodiments whichinclude a lignin gasification reactor, the reactor may be any of theabove reactors used for thermolysis or pyrolysis, or may be an up draftor down draft fixed bed reactor, for example.

Fluidised bed reactors generally require an inert medium and heat thebiomass through contact with the pre-heated particulate medium. Theinert medium may also have some catalytic activity. The biomass isintroduced into the inert bed, which is fluidized by a hot gas streampassing up through it.

An embodiment of a system and process for cellulose hydrolysis andfractionation is shown in FIG. 8. Following hemicellulose hydrolysis,such as by the system shown in FIGS. 3-7, the biomass may be preparedfor flash thermolysis by drying the biomass. The biomass is passedthrough the final dewatering high pressure screw press 78 which alsofunctions as a feed screw, for example, and into a superheated steamloop 80 through a steam loop inlet 82 for superheated steam drying thebiomass. The superheated steam loop 80 includes a blower 84 which causesthe steam and the entrained biomass to circulate through the steam loop80 to the separator 86, such as a cyclonic separator, which separatesthe steam from the biomass. The separator includes an inlet 88, a firstoutlet 90 through which the steam exits to recirculate in the steam loop80, and a second outlet 92 through which the dried biomass exits. Afterexiting the separator, the biomass may pass onto the grinding system 94.From the grinding system 94, the biomass passes into a solids feedingsystem 96, like those described above, and then into the steam reactor100 through the steam reactor inlet 102 for the separation of thecellulose from the lignin, the hydrolysis of the cellulose into vaporsof C6 sugars and other volatiles, and the formation of lignin charwithin the steam reactor 100. The thermolysis reactor may alsooptionally contain one or more of the EM/EA treatment generator 103. Thecellulose vapors and lignin char pass through the steam reactor 100 to aseparator 104, such as a cyclonic separator, in which the C6 sugar andother volatiles vapors are separated from the lignin char. The separatorincludes an inlet 106, a first outlet 108 through which the separated C6sugar vapors and steam exit the separator, and a second outlet 110through which the lignin char exits the separator.

An alternative embodiment is shown in FIG. 9. As in FIG. 8, the biomassfirst may pass through a superheated steam loop 80 for drying and agrinding system 94. The solid material including cellulose and ligninthen passes into a first steam reactor 100 for cellulose hydrolysis andthen through the separator into a second steam reactor 200. Theconditions of the first steam reactor 100 may only partially hydrolyzethe cellulose, in which case the first steam reactor 100 is a firstcellulose hydrolysis reactor and the second steam reactor 200 may be asecond cellulose hydrolysis reactor which completes cellulosehydrolysis. Alternatively, the first steam reactor 100 may completecellulose hydrolysis such that the remaining solid is comprised of onlylignin, in which case the second steam reactor 200 may be a ligninreactor for pyrolysis of lignin. The resulting product of the secondreactor may be separated by a separator 110, into phenols and char.

In FIG. 9, the second steam reactor 200 is a superheated steam tube likethe first steam reactor 100. The remaining biomass passes from the firstseparator 104 and into the second steam reactor 200. The second steamreactor 200 includes an inlet 202 and an outlet 206 through which theremaining biomass passes to a second separator 204. The second separatorincludes a first outlet 208 and a second outlet 210. In the embodimentshown, the first steam reactor 100 completely hydrolyzes the celluloseand the second steam reactor 200 pyrolyzes lignin to produce phenols.The phenols exit the separator as vapor through the first outlet 208while the remaining lignin char exits the separator through the secondoutlet 210. In alternative embodiments, or under alternative conditions,the first steam reactor 100 may incompletely hydrolyze the cellulose andthe second steam reactor may complete cellulose hydrolysis with thecellulosic products exiting the second separator 204 as vapor throughthe first outlet 208 and the lignin char existing through the secondoutlet 210.

In some embodiments, the biofractionation may include a branch afterremoval of hemicellulosic sugars and before the remaining cellulose andlignin solid proceeds to cellulose thermolysis. At this branch, a sidestream of cellulose and lignin solid may be diverted for separateprocessing. For example, the side stream may subject the solid tochemical treatment to separate the cellulose and lignin. For example, astandard wood pulp treatment, such as the sulphite process (using saltsof sulfurous acid such as sulfites or bisulfites) or the kraft process(using sodium hydroxide and sodium sulfate) or the National RenewableEnergy Laboratory (NREL) Clean Fractionation process (using methylisobutyl ketone) may be used to dissolve lignin. The resulting cellulosepulp may then be obtained as a product which may be used for paperproduction or cellulosic chemicals and fibers. Such an optional sidestream provides additional flexibility to the system.

The various systems and processes shown in FIGS. 1-9 may be usedindividually, in combination with various other fractionation systems,or may be used together in various combinations. When used together, thesystems and processes shown in FIGS. 1-9 may be used to form anembodiment of a continuous flow fractionation system for the separationof non-carbohydrates (lipids, proteins, etc.), hemicellulose, celluloseand lignin from a lignocellulosic biomass material in which the biomassflows continuously through the entire system. The continuous systemseparates the lignocellulosic material into four or more separatefractions, individually isolating the non-carbohydrates, hemicellulosesugars, cellulose sugars and lignin.

A flowchart showing an example of how the process may be used to fullyfractionate lignocellulosic biomass is depicted in FIG. 10. A singlesystem may be created by which the various options may be included andby which they may be bypassed as desired. In this way, the systemprovides a high degree of flexibility, able to accommodate any feedstockand to be adjusted to produce desired fractionation products. As shownin the example of FIG. 10, the first step of is preparation of thebiomass 302. This step may or may not be necessary, depending upon thenature of and source of the biomass. If extractives are desired, thenext step is to removal of the extractives 304. If no extractives aredesired, this step can be omitted or bypassed. The biomass then passesto the next step, which is devolatilization 306. The volatiles releasedduring this step may be isolated in the step of isolating the volatiles308. The biomass next proceeds to the steps of hemicellulose hydrolysis310 and separation of the liquid and solid components 312. The liquidcomponent may then proceed to the step of isolation of thehemicellulosic products 314. If hemicellulose hydrolysis is notcomplete, the solid may proceed through the steps of hemicellulosehydrolysis 310 and separation of the liquid and solid components 312again, though this will occur in a second hemicellulose reactor and mayuse different reaction conditions such as increased time and/ortemperature. When hemicellulose hydrolysis is complete, the solidbiomass passes to the step of cellulose hydrolysis 316. The vaporsproduced by cellulose hydrolysis are isolated in the step of isolationof cellulosic products 318. If cellulose hydrolysis is incomplete, theremaining biomass may repeat the step of cellulose hydrolysis, thoughthe process will occur in a second cellulose hydrolysis reactor and mayuse different reaction conditions such as increased time and/ortemperature. If the cellulose hydrolysis is complete, the resultinglignin char 320 may be obtained as a final product, or it may proceed tothe step of lignin pyrolysis 322 or lignin gasification 324. In analternative embodiment, after completion of hemicellulose hydrolysis310, the solid component may be used for production of fiberboard 330.

Heat may be supplied to the various reactors using a variety of means.For example, hot oil may be used as in conventional heating systems,with the reactors having hot oil jackets. In some embodiments, inductionmay be used for heating the steam and/or heating the biomass. In otherembodiments, infrared energy may be used for heating.

Various approximate residence times have been provided herein. In someembodiments, the entire process of fractionating pretreated biomass isbetween four-and-a-half and eleven-and-a-half minutes. In embodimentsthat employ a low-pressure process to separate hydrolyzed hemicellulosefrom lignin-cellulose solid in the hydrolysis stage, pretreated biomasscan be fractionated in approximately seven-and-a-half toeleven-and-a-half minutes, and raw biomass can be fully pretreated(including oil extraction) and fractionated in approximatelyfourteen-and-a-half to twenty-one minutes. In embodiments that employ ahigh-pressure process to separate hydrolyzed hemicellulose fromlignin-cellulose solid in the hydrolysis stage, pretreated biomass canbe fractionated in approximately four-and-a-half to nine minutes, andraw biomass can be fully pretreated (including oil extraction) andfractionated in approximately eleven-and-a-half to eighteen-and-a-halfminutes.

In the foregoing detailed description, the invention has been describedwith reference to specific embodiments. However, it may be appreciatedthat various modifications and changes can be made without departingfrom the scope of the invention. Thus, some of the features of preferredembodiments described herein are not necessarily included in preferredembodiments of the invention which are intended for alternative uses.

1. A method of fractionating lignocellulosic biomass materialcomprising: feeding the biomass into a devolatilization reactor toremove volatile components of the biomass; feeding the prepared biomassinto a hemicellulose hydrolysis reactor to separate and hydrolyzehemicellulose; separating the biomass into a first solid component and aliquid component, wherein the liquid component includes hydrolyzedhemicellulose in water or solvent and wherein the solid componentincludes cellulose and lignin and has less than about 10% hemicellulose;feeding the solid component into a cellulose hydrolysis reactorcomprising a continuous superheated steam reactor to hydrolyze andvaporize the cellulose component; and condensing the vaporizedcellulose.
 2. The method of claim 1 wherein the cellulose hydrolysisreactor applies steam to the biomass at a temperature of at least 300°C.
 3. The method of claim 1 wherein the cellulose hydrolysis reactorapplies steam to the biomass at a temperature of between about 400 and550° C.
 4. The method of claim 1 wherein the cellulose hydrolysisreactor applies pressure to the biomass of 1-3 bara.
 5. The method ofclaim 1 wherein the cellulose hydrolysis reactor applies steam to thebiomass at a temperature of between about 400 and 550° C. and at apressure of 1-3 bara.
 6. The method of claim 1 wherein the cellulosehydrolysis reactor applies a mixture of steam and a gas to the solidcomponent.
 7. The method of claim 1 wherein the gas comprises nitrogen,hydrogen, carbon dioxide, carbon monoxide, or combinations thereof. 8.The method of claim 1 further comprising applying electromagnetic orelectroacoustic (EM/EA) treatment to the biomass.
 9. The method claim 8wherein the EM/EA treatment includes Pulsed Electric Field, ultrasonicenergy, microwave energy, and combinations thereof.
 10. The method ofclaim 1 further comprising applying ultrasonic energy to the biomasswithin the cellulose hydrolysis reactor.
 11. The method of claim 1further comprising applying microwave energy to the biomass within thecellulose hydrolysis reactor.
 12. The method of claim 1 furthercomprising applying ultrasonic and microwave energy to the biomasswithin the cellulose hydrolysis reactor.
 13. The method of claim 1further comprising feeding the solid component into a dryer comprising acontinuous superheated steam reactor after separating the biomass in thehemicellulose hydrolysis reactor to reduce the water content of thesolid component before feeding the solid component into the cellulosehydrolysis reactor.
 14. The method of claim 1 further comprisingattriting the solid component after separating the biomass in thehemicellulose hydrolysis reactor and before feeding the solid componentinto the cellulose hydrolysis reactor.
 15. The method of claim 1 whereinthe hemicellulose hydrolysis reactor comprises a superheated steamreactor.
 16. The method of claim 1 wherein the cellulose hydrolysisreactor produces a cellulose vapor and lignin char.
 17. The method ofclaim 1 wherein the cellulose hydrolysis reactor hydrolyzes celluloseand produces a cellulosic sugar vapor and a second solid component. 18.The method of claim 17 further comprising feeding the second solidcomponent into a second cellulose hydrolysis reactor comprising asuperheated steam reactor.
 19. The method of claim 18 wherein the firstcellulose reactor partially hydrolyzes the cellulose and the secondcellulose hydrolysis reactor completes cellulose hydrolysis andseparates the vaporized cellulose from the lignin.
 20. The method ofclaim 17 further comprising feeding the second solid component into asuperheated steam reactor to reduce lignin to a condensable vapor.
 21. Asystem for fractionating lignocellulosic biomass material comprising:means for exploding cells of the biomass material; means for hydrolyzingthe biomass material to form a liquid component including hydrolyzedhemicellulose and a solid component including cellulose and lignin andless than 10% hemicellulose; means for separating the liquid componentand the solid component; and first means for hydrolyzing cellulose inthe solid component to form a cellulosic sugar vapor.
 22. The system ofclaim 21 wherein the means for hydrolyzing cellulose applies steam tothe solid component.
 23. The system of claim 22 wherein the steam is ata temperature of at least about 300° C.
 24. The system of claim 22wherein the steam is at a temperature of between about 400 and 550° C.25. The system of claim 21 wherein the first means for hydrolyzingcellulose applies a pressure of about 1-3 bara to the solid component.26. The system of claim 21 wherein the first means for hydrolyzingcellulose applies a mixture of steam and gas to the solid component. 27.The system of claim 26 wherein the gas comprises nitrogen, hydrogen,carbon dioxide, carbon monoxide, or a combination thereof.
 28. Thesystem of claim 21 wherein the first means for hydrolyzing celluloseincludes an electromagnetic or electroacoustic treatment generator. 29.The system of claim 28 wherein the EM/EA treatment generator is a pulsedelectric field, microwave, or ultrasound generator.
 30. The system ofclaim 21 wherein the first means for hydrolyzing cellulose includes anultrasound generator and a microwave energy generator.
 31. The system ofclaim 21 further comprising means for attriting the solid component. 32.The system of claim 21 wherein the first means for hydrolyzing cellulosefurther produces a lignin char.
 33. The system of claim 21 furthercomprising a second means for hydrolyzing cellulose.
 34. The system ofclaim 21 further comprising a means for vaporizing lignin.
 35. Thesystem of claim 21 wherein the means for exploding cells of the biomass,the means for hydrolyzing hemicellulose, the means for separating theliquid and solid components, and the means for hydrolyzing cellulose arein flow communication and allow the biomass to continuously flow throughthe system.